Does God still have the power to create thing or are their limits to it?

GOD knows everything!
GOD can do anything!
GOD created ALL there is!

Except in the minds of human beings, God has never existed and didn't create anything (most likely).

He can still create.

God can raise children for Abraham from the stones if He chooses. There are no limits when it comes to God's abilities, with two exceptions: He cannot lie, and He can never break His promises. All of God's decrees and promises are dependant on our obedience.

He still does

Yes, God still has the power to create.
However, you might notice that after the creation of Adam & Eve God ceased from creating. (Genesis 2:2,3)
In other words, God rested from creation ... a rest (or cessation) that God remains in yet today (See the book of Hebrews 3&4)

We are told that God will create again ... a new heaven and earth.

well, sure. He's creating things all the time.

The universe is finished, now the laws of entropy control it's fate. In Genesis 2:2 the understanding is that God “stopped” His work; He “ceased” creating on the seventh day. All that He had created was good, and His work was finished.

Simply put, God’s “rest” was not due to His being tired but to His being completely finished with His creative work.

Absolutely